Overloaded mineral wagons...is it me?

[Chubber]

I have spent a little time lately watching Yootoobe railway modelling subjects and wondering why so many coal trains, expecially PO wagons (my eyes are drawn to them in particular) are filled to the brim, even heaped high in the middle of the wagon.

 

I would like to know justhow much ended up as 'black ballast'?

 

Other than coke, wouldn't such largess inloading result in over weight stock?

 

Thinking on ballast and stone in Engineering trains, scarecely 2 planks high, tell me I'm wrong.

 

Doug

[hmrspaul]

Density of the various loads varied considerably, ballast and wet slag were very heavy compared to coal.

 

Some of the last 16ton minerals that I saw loaded with coal were unusually full, I  have several such as http://PaulBartlett.zenfolio.com/mineralmortonmxv/e6475e7f

 

Paul

[MarkSG]

Stone is about twice as heavy[1] as coal, so you can get a far larger volume of coal in a wagon before it's overloaded. I presume that the wagons were filled to the brim because the actual losses in transit were relatively low.

 

 

[1] To be more precise, stone is nearly twice as dense as coal.

[Andy Hayter]

Also to be considered as well as the density of coal versus stone, is the packing density.

 

To make clear, the density is the weight per volume of a piece of the material.  The packing density is the weight of a collection of pieces of the material per volume and the density as measured will be less than the true density because of the air spaces in between.

 

Bricks, stacked neatly side by side and on top of one another, will have packing density almost the same as solid brick, but bricks dropped randomly out of a dumper truck have a much lower packing density (they take up more space for the same number of bricks).

 

Generally the bigger the pieces, the lower will be the packing density if there is ransom stacking - so large lumped coal has a much lower packing density than nugget sized ballast stone. 

 

So not only do we have the effect of differences in absolute density we also have differences due to packing density and the different size of the materials being carried.

[black and decker boy]

Also to be considered as well as the density of coal versus stone, is the packing density.

 

To make clear, the density is the weight per volume of a piece of the material.  The packing density is the weight of a collection of pieces of the material per volume and the density as measured will be less than the true density because of the air spaces in between.

 

Bricks, stacked neatly side by side and on top of one another, will have packing density almost the same as solid brick, but bricks dropped randomly out of a dumper truck have a much lower packing density (they take up more space for the same number of bricks).

 

Generally the bigger the pieces, the lower will be the packing density if there is ransom stacking - so large lumped coal has a much lower packing density than nugget sized ballast stone. 

 

So not only do we have the effect of differences in absolute density we also have differences due to packing density and the different size of the materials being carried.

That only affects the volume the load will take as the wagons will generally be loaded by tonnage (hence weigh bridges at collieries and quarries). 1T of loose coal weighs the same as 1T of solid coal, it just takes up a bit more volume. The volume taken up will alter over the journey as the load will consolidate from vibrations.

 

In modern wagons, the capacity / physical size of the wagon is made to match the intended load.nthe national power bogie hoppers for limestone are much shorter than the matching rakes intended for coal and the new biomass wagons are longer and a totally different design philosophy to cater for the very low density of biomass pellets.

[Arthur]

 

Andy's point about packing density is still an important consideration in wagon loading and it's subsequent appearance. Matching weight capacity to volume, as in your National Power example, is all very well if the wagons are in a dedicated service and always carry the same material.

 

Wagons in general service will carry different bulk materials whose density and packing density vary, so, when loaded to maximum weight, the wagon may appear only half full, full, heaped or even be heaped and actually underweight if loaded with, say, coke.

 

Iron ore is a good example. Not only do the ores vary in weight, if excavated in big lumps, it'll have a low packing density, processed or beneficated ores will not only be heavy because of their high iron content, they are of a crushed or pelleted nature which packs together very densely.

[Spitfire2865]

I feel the original question was why models of simple 4 wheel opens often show heaps of coal a foot or so over the top of the sides.

 

Then it just spiraled into density vs weight and how modern stock is designed.

 

To go back to the OPs question,

I see heaps, but not overflowing. Definitely has enough room to be smoothed flat and still not overflow. Just how stuff falls. Tall in the middle with sloping sides.

[Arthur]

 

The OPs question can only be answered by understanding the factors which determine real wagon loading, it's all about density and weight so I fail to see how it's spiralled. Doug mentions coal, stone and ballast and we've been discussing why those loads look different.

 

Understand those factors and you can produce realistic model loading for any material. Or know when you see a poorly modelled load.

[Andy Hayter]

That only affects the volume the load will take as the wagons will generally be loaded by tonnage (hence weigh bridges at collieries and quarries). 1T of loose coal weighs the same as 1T of solid coal, it just takes up a bit more volume. The volume taken up will alter over the journey as the load will consolidate from vibrations.

 

 

 

 

Absolutely correct, and that is why a coal wagon was a seven or eight plank open and a ballast wagon might only be a two plank one.  The simple difference in density between ballast stone and coal would suggest that ballast would require a wagon half the height of a coal wagon, but the packing density differences mean that the ballast wagon is smaller than the simple density difference might suggest.   This was one of the points questioned by the OP and I think we have explained it.

[Rivercider]

The difference between the relative density of coal and stone/ballast can be illustrated by the 16t minerals which were transferred to the civil engineers department in the 1980s.

Very quickly there were problems of overloading due to the greater density of the spent ballast, the solution was to cut rectangular holes in the sides to prevent overloading,

 

https://www.flickr.com/photos/tutenkhamunsleeping/5434671212/in/photolist-9hf7pN-pEzsVW-bAD993-jgWQJq-ay2cwr-kNzyLH-dvpZPF-9hbXZZ-oWXjTN-d1TuRA-oVH5Ts-bZzp2b-bZBhoj-m38QBC-dBoXYC-pExQUr-dBiwxB-hSkbDq-cZx4Uw-oH6JAu-9x1gLm-dgWUsN-oBRsjU-ddqEn8-4rwLBc-aoEexh-dgWTNn-bah48X-p67hYE-e3hipC-dgWTCM-dgWTC9-dgWTWG-dgWTMC-dgWT2D-dgWSGw-fFiFNK-dgWSLx-knGbtn-9PWFXZ-dgWSRW-dgWSCz-dgWRSX-b95pr6-dgWS3e-dgWSUi-b97FNg-b9HUw2-b97Fw4-b97Eyi

 

cheers 

[jonny777]

When I watched the High Dyke - Frodingham iron ore trains, from the back garden, there were occasional 16t coal wagons in amongst the 27t tipplers. I often wonder how they managed to get in there, and how long the springs lasted after ~27 tons of ore was dropped onto them.

[Arthur]

 

The point is that they shouldn't have had 27 tons if ore in them, they should have been loaded to their rated weight. Photographs of such wagons carrying ore and looking almost empty, despite carrying their maximum rated load, have been commented on before.

 

That's not to say that they were never overloaded though I would imagine BR inspectors would have been vigilant enough.

[teaky]

Would the ore have been loaded in one go or two?  I've seen pictures of larger wagons with two mounds of minerals in them.  If this also applied to the ore trains then perhaps the 16 tonners only got one 'pile' instead of two?

[kevinlms]

Would the ore have been loaded in one go or two?  I've seen pictures of larger wagons with two mounds of minerals in them.  If this also applied to the ore trains then perhaps the 16 tonners only got one 'pile' instead of two?

My guess is that it would depend on the type of loading facility. A conveyor belt would be different to a scoop from an excavator, for example.

 

I remember reading an article somewhere, where someone claimed he could tell where MGR coal hoppers were loaded, by the shape & number of humps.

[Arthur]

 

Depends on the ore and the loading facility. That loaded direct by face shovel at the ore pit would be three or four bite sized chunks or slabs. Much home, UK ore, was delivered that way. Imported ores, and some domestic ores, were pre treated to remove some of the waste and reduce transport costs prior to shipping. Such ores were dry, and crushed or pelletised, and flowed freely.They would be loaded by grab crane, special ore cranes (Cargo Fleet and Bidston dock) or overhead bunker (Tyne Dock). The loading method would determine the number of 'humps'.

[Rivercider]

I feel the original question was why models of simple 4 wheel opens often show heaps of coal a foot or so over the top of the sides.

 

Then it just spiraled into density vs weight and how modern stock is designed.

 

To go back to the OPs question,

image.jpg

I see heaps, but not overflowing. Definitely has enough room to be smoothed flat and still not overflow. Just how stuff falls. Tall in the middle with sloping sides.

I think this yard full of export coal is either at or near a docks awaiting shipment?

That being the case after loading the wagons will have been shunted at least once or twice

then travelled on an unfitted train for ten or twenty miles before being shunted again.

If the wagons had been loaded to the top of the sides then any spillage would have taken place in the colliery

or nearby yard and the coal would have settled in transit a bit by the time this photo was taken,

 

cheers 

[The Stationmaster]

When I watched the High Dyke - Frodingham iron ore trains, from the back garden, there were occasional 16t coal wagons in amongst the 27t tipplers. I often wonder how they managed to get in there, and how long the springs lasted after ~27 tons of ore was dropped onto them.

Overloading and uneven loading (usually a result of using bucket loaders) was a problem in the early days of the West of England stone trains using ex iron ore tipplers and even some 16 tonners.  Outsiders, especially inexperienced outsiders tend to see a railway wagon as a box to fill with whatever they are loading - so they fill it.

 

The result is hot boxes, other damage, and derailments - the latter sometimes being quite serious and/or spectacular.  Specialised loading equipment using overhead conveyors normally loads on the centreline and a skilled operator can ensure fairly even distribution along the length of the wagon while the machine itself  - if correctly set for the wagon(s) being loaded - prevents overloading.

 

Similarly most collieries loaded coal at screens which put the load mainly on/near the centreline and skilled men would sure sensible distribution along the length of the wagon that sort of loading is reflected in the wagons waiting shipment order in the Cardiff (I'm pretty sure it's Cardiff) picture in post No.7.  The load is heaped in the middle of the wagon because that is where it was loaded, it spread from there as more coal was tipped in but usually remained higher in the centre.  The picture of course comes from the era when colliers were not paid for small coal hence you don't see any really small stuff - that went on the mine's tip.

[br2975]

I think this yard full of export coal is either at or near a docks awaiting shipment?

It is - Cardiff Marshalling Sidings - basically alongside the rainforest c*m jungle that is now known as Tidal Sidings.

.

Brian R

[corneliuslundie]

And since they were paid by the ton collieries would weigh each wagon and ensure they were not giving any away.

[ZiderHead]

For reference, here is a list of some common bulk materials and how much they would weigh if a 16t minerals wagon were fully loaded with them (e. level to the top):

 

24t Bauxite, crushed
28t Cement - clinker
34t Clay, wet excavated
20t Coal, Anthracite, broken
15t Coal, Bituminous, broken
12t Coke
44t Concrete, Gravel
44t Concrete, Limestone with Portland
48t Copper ore
26t Earth, moist, excavated
29t Earth, wet, excavated
32t Earth, soft loose mud
26t Flint - silica
139t Galena ( lead ore )
30t Granite, broken
35t Gravel, with sand, natural
31t Gravel, dry 1/4 to 2 inch
37t Gravel, wet 1/4 to 2 inch
53t Iron ore - crushed
28t Lime, stone, lump
26t Limestone, pulverized
29t Marble, broken
35t Mud, packed
30t Sand with Gravel, dry
37t Sand with Gravel, wet
29t Shale, broken
22t Slag, crushed, 1/4 inch
25t Slate, pulverized
29t Stone, crushed
10t Wood chips - dry

 

 

edit: this is just a selection of the 340ish materials I have on a spreadsheet, I'm guessing the density of Alfalfa, ground won't be relevant to many modellers, and I haven't even heard of a lot of the stuff. Wool surprised me though - 24t!

[Andy Hayter]

Wool is light(ish) fluffy stuff and transporting it, as is, would be a bit like transporting expanded polystyrene.  Since transportation costs are based more per wagonload than per tonne, the solution for wool (but not for expanded polystyrene) is to compress the wool into compact bales where a lot of the air between the fibres has been squeezed out (effectively increasing the packing density many times over).  By doing this you can get very high laden weights that would otherwise not be possible.

[Fat Controller]

From experience of coal-carrying lines in South Wales and elsewhere, I can say that quite a lot of coal did find its way on to the track, either by falling off the top or, more usually, leaking around doors and other apertures.

Sometimes, the railway got the choice of wagon for a job horribly wrong, however. One example I saw was what was meant to be a trial run of anthracite from Onllwyn to Mossend, composed of  a selection of odds'n'sods. The MEAs were a reasonable enough choice; the same couldn't be said for the couple of 'Limpets', borrowed from the engineer's fleet, where they'd been modified to carry spoil. I saw them at Margam, by when (after perhaps thirty miles), half the load had trickled away. I wonder how much got to Scotland?

[kevinlms]

For reference, here is a list of some common bulk materials and how much they would weigh if a 16t minerals wagon were fully loaded with them (e. level to the top):

 

24t Bauxite, crushed

28t Cement - clinker

34t Clay, wet excavated

20t Coal, Anthracite, broken

15t Coal, Bituminous, broken

12t Coke

44t Concrete, Gravel

44t Concrete, Limestone with Portland

48t Copper ore

26t Earth, moist, excavated

29t Earth, wet, excavated

32t Earth, soft loose mud

26t Flint - silica

139t Galena ( lead ore )

30t Granite, broken

35t Gravel, with sand, natural

31t Gravel, dry 1/4 to 2 inch

37t Gravel, wet 1/4 to 2 inch

53t Iron ore - crushed

28t Lime, stone, lump

26t Limestone, pulverized

29t Marble, broken

35t Mud, packed

30t Sand with Gravel, dry

37t Sand with Gravel, wet

29t Shale, broken

22t Slag, crushed, 1/4 inch

25t Slate, pulverized

29t Stone, crushed

10t Wood chips - dry

 

 

edit: this is just a selection of the 340ish materials I have on a spreadsheet, I'm guessing the density of Alfalfa, ground won't be relevant to many modellers, and I haven't even heard of a lot of the stuff. Wool surprised me though - 24t!

Very good, some of those loadings wouldn't do the wagons any good at all, even before anyone attempted to move them! I'm surprised at dry wood chips, being more than half the weight of coal.

[w124bob]

Heading for Rugeley with a train from the Coalville area every HAA was at least a couple of tons over weight(according to the TOPS list). Looking back down the train once on the WC mainline at Litchfield you could rarely see the back of the train on dry days, just a black cloud !

[Reorte]

And nothing on that list is 16t... Bituminous coal at 15 suggests a bit of room for error and I suppose it getting damp could add up to a fair bit extra.

 

Interesting post about the modern wagons further up, is the size variation due to keeping axle weights acceptable?